1. Field of the Disclosure
The present disclosure relates to a light-emitting diode (LED) module, and more particularly, to a LED module having an increased lifespan achieved by improving the degradation characteristics of a phosphor material when producing white light or other monochromatic light using a phosphor material and a LED emitting ultraviolet (UV) or blue light.
2. Description of the Related Art
LEDs are light-emitting sources made of a compound semiconductor, such as GaAs, AlGaN or AlGaAs, and generate light of various colors. Because LEDs are easier to fabricate or control than semiconductor lasers and have a longer lifespan than fluorescent lamps, they are emerging as promising illumination light sources for a next-generation display by replacing fluorescent lamps. With the recent advent of blue and UV LEDs made possible by using a nitride having excellent physical and chemical characteristics and because a blue or UV LED or phosphor material can be used to produce white light or other monochromatic light, LEDs are being used in a wider range of applications. For example, in a white LED module, UV light emitted from a LED chip excites phosphor materials to emit visible light of three primary colors—red (R), green (G) and blue (B)—or visible light of yellow (Y) and blue (B). The colors of the visible light emitted from the phosphor materials vary depending on the composition of the phosphor materials. When combined, all the colors of visible light appear to be white to human eyes.
FIG. 1 illustrates the structure of a conventional LED module. Referring to FIG. 1, the conventional LED module includes a light-emitting chip 1 disposed inside a concave slot within a base 6, and a first resin layer 3, a phosphor layer 4 filled with phosphor materials and a second resin layer 5 formed sequentially within the base 6. When light emitted from the light-emitting chip 1 is incident on the phosphor layer 4, energy is transferred to the phosphor materials so as to emit light having a longer wavelength than the incident light, thus creating white or monochromatic light. During this process, the phosphor materials are degraded due to heat generated by driving the light-emitting chip 1 and generated by converting the light emitted by the light-emitting chip 1 into light of a wavelength different than the light emitted by the light-emitting chip 1. Degradation of phosphor materials results in a reduced lifespan for the LED module. Thus, there is a need to improve the degradation characteristics of phosphor materials for the fabrication of a long life LED module.